Jean Pierre TEMGA

Characteristics, Source Area-weathering, Sedimentary Processes, Tectonic Setting and Taxonomy of Vertisols Developed on Alluvial Sediments in the Benue Trough of North Cameroon

Primus Azinwi Tamfuh, Jean Pierre Temga, Émile Temgoua, Emmanuel Djoufac Woumfo, Philémon Zo’o Zame, Milan Stafford Tchouatcha et 3 autre(s)

Journal of Geosciences and Geomatics

Although Vertisols have been highly documented owing to technological breakthroughs, numerous aspects are still not fully understood such as implication of geochemistry on source area-weathering, provenance, tectonic setting and sedimentary processes as well as problems of classification and management. This work aims to highlight the geochemical characteristics of Vertisols formed on alluvial deposits in the Benue Basin of North Cameroon and to highlight their source area-weathering, sedimentary processes, tectonic setting, taxonomic level and possible management strategies. The work was done in the field and in the Laboratory. The main results showed that smectite is the predominant clay mineral. Chemical composition revealed high Si, Al and Fe contents. Heavy minerals contents are of plutonic (augite, aegerine and aegerinic augerinic augite), metamorphic (kyanite, sillimanite and andalusite) and volcanic (tourmaline) origin. This agrees with the Al2O3/TiO2 ratio of 8.72 to 30.40 reflecting sediments from felsic rocks and minor mafic rocks. The CIA (chemical index of alteration: 70 to 85), PIA (plagioclase index of alteration: 66 to 82) and Ruxton’s index (SiO2/Al2O3: 2.27 to 3.55) suggest a warm and humid climate during moderate to intense chemical weathering probably prevailing during a more humid pre-depositional period. The K2O/Na2O ratio <1 suggests high sediments chemical maturity. The predominance of angular quartz grains suggests short fluvial transport distance and low sorting. The tectonic setting discrimination ternary diagram indicates that alluvial sediments, parent material of Vertisols, originate from an Active Continental Margin while the discriminant function-based multidimensional tectonic diagram indicates an arc-collisional setting suggesting that parent materials are from the Pan-African basement of the Central African Fold Belt. The Vertisols are classified as Ustic Haplusterts Clayey Isohyperthermic (United States Department of Agriculture) and as Gleyic Stagnic Vertisols (Pellic, Hypereutric, Clayic) (World Reference Base for Soil Classification).

• #geochemistry and elemental analysis
• #geological and geophysical studies worldwide
• #paleontology and stratigraphy of fossils
• #geology

Geochemical Characterization of Vertisols Developed on Granites from Kaele, North-Cameroon: Implications for REE Exploration

Jean Pierre Temga

World Journal of Agriculture and Soil Science

This paper presents the geochemical features of Vertisols developed on granites from Kaele, North Cameroun. The mineralogy of soil samples was determined by X-ray diffraction (XRD). X-ray Fluorescence (XRF) and Inductively Coupled Plasmas-Mass Spectrometry (ICP-MS) have been used to determine major and trace element including rare earth elements compositions of granite and soil samples. Granite samples consist of feldspars (orthoclase, plagioclase), quartz, biotites and opaque minerals. They have peraluminous composition and of S-type granite. They also have high contents in Ba, Cr, Sr, Zr and low REE contents with variable Eu anomaly values. The mineralogical and geochemical features of Vertisols corroborate with the parent rock nature and the intensity of weathering process. The Fe-oxide precipitation, the presence of kaolinite and calcareous nodules are responsible for significant contents in Fe2O3, Al2O3 and CaO, respectively. Several major and trace elements are accumulated at the bottom of the profiles. The accumulation of clay increases with REE contents from the upper to the lower horizons in Vertisols of Kaele area. LREE-enrichment in Vertisols is inherited from the parent material and probably preserved by the formation of secondary LREE-bearers. The low REE contents may result from depletion of REE rich minerals as in the parent rocks despite the REE remobilization during weathering. REEs how coherent geochemical behavior and low solubility during weathering. The variable Eu anomalies can be explained by the variable behavior of Eu-bearers while Ce anomalies exhibit the variability of the oxidation conditions. The low (La/Yb)N values and the similarity of the spectra of mass balance calculation in most of the profiles are linked to the environment which is not well drained and the homogenization of the profiles by seasonal deep surficial desiccation cracks.

• #geochemistry and elemental analysis
• #geochemistry and geologic mapping
• #clay minerals and soil interactions
• #weathering

Erodibility of Vertisols in relation to agricultural practices along a toposequence in the Logone floodplain

Simon Djakba Basga, Jean Pierre Temga, Désiré Tsozué, Arafat Gove, Sali Bourou, Jean Pierre Nguetnkam

Soil & Environment

Knowledge of the combining effect of agricultural practices and slope on soil erodibility is important to promote their suitable use and constitutes a key parameter for their sustainable conservation. The aim of this study was to characterize vertisols from the Logone floodplain and evaluate their erodibility in relation to the agricultural practices and slope in order to suggest the well managing strategies to be diffused. Vertisols were characterized by describing their profile type and their erodibility was assessed by sampling topsoils at 3 positions along a toposequence (upslope, midslope and footslope). Erodibility indexes were computed by exploiting physicochemical data. The studied vertisols were classified as gleyic Vertisols. They are clayey (19-42% of clay), slightly basic (pH~7.3) and display high organic matter (OM) content and cation exchange capacity. Smectites and kaolinite were the main clay minerals associated with quartz. The water dispersible clay, clay dispersion ratio and dispersion ratio diminished from the upslope to the footslope, while clay aggregation showed an opposite trend. Hence, vertisols from the upslope and midslope cropped were more erodible than those from the not cropped footslope. From the statistical analysis, it appeared that Na + , Ca ++ and K + contributed to vertisols erodibility while Mg ++ , OM and amorphous Fe promoted aggregate stability. Managing these vertisols will tend to limit N and K rich inputs (urea and NPK fertilizers); control liming strategies and encourage substantial OM inputs. No-tillage or minimum tillage oriented perpendicularly to the slope are the practices to be implemented.

• #soil erosion and sediment transport
• #soil management and crop yield
• #soil carbon and nitrogen dynamics
• #vertisol

Ceramics applications of clay in Lake Chad Basin, Central Africa

Jean Pierre Temga, Jacques Richard Mache, Achille Balo Madi, Jean Pierre Nguetnkam, Dieudonné Bitom

Applied Clay Science

• #recycling and utilization of industrial and municipal waste in materials production
• #clay minerals and soil interactions
• #therapeutic uses of natural elements
• #kaolinite

Variation of Soils Erodibility in Mbe Agropastoral Area in Relation with Land Utilization, Central Cameroon

Boukar Atougour, Simon Djakba Basga, Elisabeth Yaboki, Jean Pierre Temga, Jean Pierre Nguetnkam

Open Journal of Soil Science

The study of the soils from Mbé and Wack is carried out in the framework of the knowledge of soils from the Adamawa Region of Cameroon and their erodibility was investigated using erodibility indices obtained through physico-chemical data. Eleven topsoils (0 - 20 cm) samples were collected on different land use and their susceptibility to erosion was assessed. The water dispersible clay (34.92 - 121.75 g•kg−1), the clay dispersion ratio (0.45 - 0.84) and the dispersion ratio (0.75 - 0.89) were high in the studied soils while the clay aggregation (13.16 - 42.27g•kg−1) and the clay flocculation index (0.16 - 0.55) were low to moderate indicating their high erodibility. The soils under natural vegetation, more clayey, displayed the highest amount of water dispersible clay while cropped soils recorded the smaller ones. Globally, in cropped soils, those under cereals displayed the highest clay dispersion indices than those under tubers. This suggests that tubers cropping practices in studied soils enhance their erodibility. Statistical analyses revealed that amorphous Al and Fe are elements which limit soils erodibility while K+ and promote soils particles dispersion. Sustainable management of these soils will consist on limiting runoff through agricultural practices such as direct seedling and orienting tillage perpendicularly to slope gradient.

• #soil erosion and sediment transport
• #soil carbon and nitrogen dynamics
• #aeolian processes and effects
• #soil water

Land use impact on clay dispersion/flocculation in irrigated and flooded vertisols from Northern Cameroon

Simon Djakba Basga, Désiré Tsozué, Jean Pierre Temga, Jules Balna, Jean Pierre Nguetnkam

International Soil and Water Conservation Research

Clay dispersion by water is important for soil and water conservation as well as for irrigation scheduling. In the present study, clay dispersion/flocculation of irrigated and flooded vertisols in North Cameroon was investigated using clay dispersion/stability indices. Nine vertisols topsoils (0–20 cm) samples were collected on different land use and their clay dispersion indices were assessed. Vertisols were acidic to slightly basic, with smectites as dominant clay mineral. The water dispersible clay (160–340 g kg −1 ), the dispersion ratio (0.55–0.79) and the clay dispersion ratio (0.48–0.83) were high in the studied vertisols while the clay flocculation index (0.17–0.54) and the clay aggregation (70–230 g kg −1 ) were low to moderate, indicating their high dispersion. Cropped vertisols displayed the higher amount of water dispersible clay while not cropped recorded the smaller amount. Concerning the cropped soils, irrigated vertisols displayed the highest clay dispersion indices suggesting that agricultural practices (irrigation) enhance clay dispersion. Globally, the clay dispersibility trend was: irrigated paddy ˃ rainy sorghum ˃ rainfed paddy ˃ dry-season sorghum ˃ not cropped. Statistical analyses revealed that amorphous Al, Na + and electrical conductivity enhance clay dispersion while organic matter, nitrogen and Ca ++ promote clay flocculation/aggregation. The overall findings emphasized that practices such as heavy tillage and irrigation induce clay dispersion. Minimum tillage, electrolytes concentration monitoring in irrigation water, irrigation scheduling based on soil moisture control, organic matter inputs and implementation of adapted dams are measures susceptible to limit their degradation through clay dispersion.

• #soil and unsaturated flow
• #clay minerals and soil interactions
• #soil erosion and sediment transport
• #vertisol

INTERNATIONAL UNIVERSITY COOPERATION FOR VALORIZING CRUDE EARTH AS BUILDING MATERIAL IN CHAD AND CAMEROON

Jean Pierre Temga, Vitali

Institutional Research Information System (Università degli Studi di Brescia)

Deforestation is one of the most dramatic threats to environmental equilibrium and food safety in many regions of the world, and particularly in sub-Saharan Africa. It is enhanced by many kinds of human activities, among which is the earth brick firing process, that needs large amounts of wood for attaining and maintaining temperatures required during this process. Crude earthen bricks can be used as an alternative for buildings, with environmental benefits; however, the economical and social sustainability of this building technique is linked to the improvement of the brick production technology, based on a deeper knowledge of the local resources. For this reason, a partnership was developed between an Italian University and a Cameroonian one for valorizing crude earth as building material in the Logone valley, located at the border between Chad and Cameroon: this way, the knowledge of the local context owned by the Cameroonian university was an added value to the technical skills of both universities, driving the choices made during the project. The Cameroonian university carried out mainly morphological and geotechnical analyses on soils, in order to choose the best site for brick production in the region; the Italian university designed and followed the realization of a machine for improving brick production. As a result, a pilot plant for crude earth brick production was installed.

• #hygrothermal properties of building materials
• #geotechnical and construction materials studies
• #natural fiber reinforced composites
• #earth (classical element)

Valorisation of crude earth as sustainable building material: a case of international cooperation in the Logone Valley (Chad–Cameroon)

Jean Pierre Temga, Angelo Mazzù, Jean Pierre Nguetnkam, Daniela Palazzini, Robert Ndjouenkeu, Francesco Vitali

International Journal of Sustainable Engineering

Deforestation is one of the most dramatic threats to environmental equilibrium and food safety in many regions of the world, and particularly in sub-Saharan Africa. It is enhanced by many kinds of human activities, among which is the earth brick-firing process that needs large amounts of wood for attaining and maintaining temperatures required during this process. In order to reduce deforestation, the present study investigated from different points of view the potential of crude earth to be used as building material, taking as a case study the Logone Valley located at the border between Chad and Cameroon. First, an on-site investigation was made to verify the state-of-the-art of brick production technologies and to evaluate their impact on the environment. Subsequently, morphological and geotechnical analyses on soil samples collected from different sites of the Logone Valley were carried out, to evaluate their suitability to brick production. Finally, a pilot plant for crude earthen brick production was set, particularly based on a new press designed for this purpose.

• #hygrothermal properties of building materials
• #geotechnical and construction materials studies
• #brick
• #deforestation (computer science)